This invention relates to an apparatus and a method for the fusion processing of synthetic thermoplastic resinous materials. More particularly, the invention relates to the processing of a particulate synthetic thermoplastic resinous material by the use of a high-velocity stream of heated gas to transport the particulate synthetic thermoplastic resinous material through an elongated passageway which directs the stream of gas and particulate resinous material onto a workpiece, thereby causing the particulate resinous material to fuse onto the workpiece as a continuous mass.
It is known to mix a synthetic thermoplastic resinous material, in powder form, with a gas stream, which gas stream transports the material to a workpiece to be coated. Such a method depends on a flame or on excessive internal heating of the gas stream to melt the resinous material. Supplying heat in these ways often causes plugging of the apparatus or degradation of the resinous material. The present invention provides a means of processing particulate synthetic thermoplastic resinous materials without the use of a flame or excessive internal heating. The invention also provides a novel method of minimizing or eliminating plugging of the apparatus or premature sintering of the thermoplastic resin that is being processed. Other advantages dervied from this novel processing technique are greater versatility, simplicity of equipment design and operation, and lower capital costs.